Sony makes a very good Memory stick pro duo, 16 G, that's about 85 as I recall. It is what is recommended for the camera so that's what I bought. Don't know what the write speed is, read it somewhere, but, you will be limited in extended shooting by the buffer in the camera, not the memory write. Supposed to shoot at 3 fps which seems right whether raw or jpg, but I've shot a lot of frames one after the other in raw and rarely had to wait for the buffer to dump. If you shoot craw it's a little faster, jpgs go with a lot of exposures on continuous shoot before it even slows down. I also have an 8G in my 700 and those are the only two I have. Can't imagine filling up a 16G card even in raw but I suppose it could happen. Sony has a warning on it's site about counterfeit memory chips that could screw up the camera. I figured with so much cash tied up in a camera why mess around trying to save a buck on a memory chip.